The invention includes a device having a chamber within a syringe. A fluid passageway extends through a syringe piston. A valve is associated with the passageway controlling fluid passage through the piston. The invention includes a piercing structure having a head segment and a body portion, with a channel through the body portion and through at least one surface of the head without passing through the tip. In another aspect the invention encompasses a method of preparing an agent for administration to an individual. A first component is provided within a syringe and a second component is provided within a vial. A closed valve is associated with a fluid passageway between the vial and the syringe barrel through a piston. Valve repositioning allows fluid passage and sliding of the piston joins the first and second components. Repeated sliding of the piston mixes the components to produce the medication agent.